1. Field of the Invention
The present invention relates to a belt driven-type electric rotating machine for vehicle that is connected to an engine, and to an electric rotating machine for vehicle that is provided with a control device controlling a belt driven-type electric rotating machine for vehicle.
2. Description of the Related Art
For example, the Japanese Patent Publication (unexamined) No. 156589/2004 shows an idle stop control device (see FIGS. 9–11 and descriptions in columns 0068 to 0072 thereof). This known control device includes a switching element that is directly fixed onto a substantially disc-shaped heat sink, and a circuit board having a printed wiring layer that is fixed onto the heat sink; and a control IC and the like is mounted on the circuit board. Furthermore, this heat sink has double side frames attached around the entire outer circumference and the entire inner circumference, and is fixed to the rear end outer wall of a bracket via the outer circumferential side frame. Resin is injected into a ring-shaped concave part surrounded by the inner and outer circumferential side frames of the heat sink, whereby the switching element, the circuit board, the control IC, and the like are easily protected from environmental factors such as salt or mud water, resulting in improved durability and reliability.
Moreover, in the control device, a resin cover is fixed to the bracket covering the heat sink. Thus, this control device has such a cooling system that a cooling air flowing in through an air inlet that is formed in the resin cover flows in the bracket while cooling the heat sink to cool a stator winding or a rotor winding, and is discharged from the bracket to the outside.
However, in the case where a circuit board is located in the vicinity of the heat sink to which a switching element, being a heat generation element, is fixed, a problem exists in that electronic parts of low heatproof temperature such as control IC formed on the circuit board are thermally damaged. Moreover, since electronic parts are integrally sealed with resin, heat from the switching element is likely to conduct to the circuit board through the resin causing a temperature of electronic parts on the circuit board to rise.
Further, originally, a control circuit section that is formed of electronic parts or board of low heat-resistance is susceptible to the influence of heat, and parts or board usable at high temperature are expensive. Consequently, another problem exists in high cost of the whole system.
Furthermore, since a substantially disc-shaped heat sink is utilized as the frames for plastic-sealing a switching element or a circuit board, the configuration or layout of a heat sink is restricted. As a result, a further problem exists in more difficult cooling design of a control device, resulting in a larger capacity of a heat sink.
Moreover, as to the flow of cooling air flowing in by means of a centrifugal fan, cooling air being got in through an air inlet of the resin cover flows on a substantially disc-shaped heat sink toward a center thereof, flows in the bracket through small clearances on the inner circumference side of the heat sink, and is discharged toward a radial direction from the bracket. Therefore, there is a large pressure loss in cooling air, or a large loss due to deflection of a cooling air passage, eventually resulting in worse cooling efficiency.
Further, since it is constructed such that a heavy article such as heat sink is located at a position distant from the bracket, a still further problem exists in insufficient strength against vibration, etc.
The invention was made to solve the above-described problems and proposes a structure capable of protecting a control circuit board from the defect such as electric corrosion due to environmental factors such as salt water, while improving cooling performance of a power unit, and a structure of easy assembling and high productivity.